A microfluidic chip developed at the University of Michigan is among the best at capturing elusive circulating tumor cells from blood—and it can support the cells' growth for further analysis. The device, believed to be the first to pair these functions, uses the advanced electronics material graphene oxide. In clinics, such a device could one day help doctors diagnose cancers, give more accurate prognoses and test treatment options on cultured cells without subjecting patients to traditional biopsies.